This issue has been observed on Redhat 7 using Samba 4.7.1-6 and 4.7.1-9
This is caused by the following Samba command failing:
net -f -i changesecretpw
3rd party issue.
Note that the net command is part of the Samba code and not Authentication Services.
Please contact your Samba support to determine if a fix is available for the net command issue.
Use Samba 4.6 while waiting for a fix from your Samba support.